61 



the area where disease had been distributed, and two days later exam- 

 ples were found a quarter of a mile from the starting point of the dis- 

 ease. Immediately after this, however, another halt, both in the in- 

 tensity of attack and rapidity with which it spread, due either to the dry 

 weather, or to the fact that the bugs had now all reached the adult 

 stage, and had become diffused over the country, no longer congregat- 

 ing together. From either one or the other, or both of these causes, 1 

 lost track of the Entomophthora and was not able to again find it in the 

 fields. It seems proper to state here that Chinch Bugs were not at any 

 time excessively abundant. The greatest numbers were in the exact 

 localities where the disease was first distributed, the congregating at 

 these places being brought about by the close proximity to a large num- 

 ber of small experimental plats of wheat, and when this was harvested 

 the bugs collected en masse on the corn and young wheat. In connec- 

 tion with these facts, it is also interesting to note that from July 15 to 

 August 31 there were ten days on which rain fell. The dates of these 



rains and the amount of precipitation is given 



below : 





Date. 



Precipi- 

 tation. 





Date. 



Precipi- 

 tation. 



July 17 



Inches. 

 .02 

 1.25 

 .20 

 .04 

 .13 



July 29 



Inches. 



.78 



19 



30 



.50 



22 



Aug. 9 



3.36 



23 



13 



.15 



26 



14 



.02 









With a view of learning whether or not there was any difference as 

 regards susceptibility to the attack of Untomoplithora, between bugs in 

 different stages of development, a series of experiments was begun, as 

 follows: 



Young plants of Setaria glauca were transplanted to a box, and upon 

 each plant was placed a dead bug covered with the fungus, and also 

 healthy larvae ; larvae just on the point of pupation; pupae just prior to 

 reaching the adult stage; and fully developed adults, each stage being 

 placed on separate plants and each covered with a small inverted glass 

 vial numbered by lettering. As checks, another series was prepared 

 like the first in every particular. The soil in the box was kept well 

 moistened, and the plants remained fresh. This experiment was made 

 on August 2, about the time when the attack outside began to diminish 

 in intensity. The following are the results of examinations on the 

 dates indicated, the original experiments being numbered by capitals, 

 and the checks by small letters, thus — A-a, adult: B-b, young larvae ; 

 C-c, older larva? ; D-d, pupae. 



Date. A. 



a. 



B. 



b. 



C. 



c. 



D. 



d. 



Aug. 5 Healthy .. 

 Aug. 6 1 dead ... 



Healthy . . 

 1 dead 



Healthv . 

 Healthy 



Healthv . 

 Healthy. 



1 dead . .. 



1 dead . . . 



1 dead ... 

 3 dead . . . 

 All dead . 



Healthv . 

 Healthy . 



1 dead ... 

 3 dead . . . 



1 dead. 

 L dead. 



5 dead. 



Au-r.16 All dead.. 



All dead .. 



All dead. 



All dead 



All dead . 



All dead 



All dead. 



